MINNEAPOLIS (WCCO) – Democratic voters in Minneapolis got together this weekend to pick their preference for the city’s next mayor.

They couldn’t reach a decision, but if the recent past is any indication, the next mayor of Minneapolis will be a DFLer.

Of the 25 biggest U.S. cities, only Indianapolis and Fort Worth have Republican mayors.

So why are most major cities headed by Democrats?

The last Republican mayor in Minneapolis served from 1957 to 1961. Before then, the parties would switch every few elections.

Mayor R.T. Rybak says while Minneapolis has some of the state’s poorest and richest residents, it’s not the political views of the residents that have shifted over time.

“I grew up in southwest Minneapolis, and at the time I was growing up it was the most Republican part of the state,” Rybak said. “Today it’s the most democratic part, and the people haven’t changed that much.”

Dr. Kathryn Pearson of the University of Minnesota backs up Rybak’s observation.

“There were plenty of moderate and even liberal Republicans during the 1950s, but that’s just not the case today, when most Republicans tend to be conservative and most democrats tend to be liberal,” Pearson said.

She says more residents of urban areas identify themselves as Democrats.

“Urban areas tend to be more diverse, but diverse in ways that favor the Democratic Party,” she said, referring to populations of color, the LGBT community or lower-income families.

Minorities are more likely to live in cities. According to CBS News exit polls from the 2012 election, 93 percent of blacks and 71 percent of Hispanics voted for Democratic President Obama compared to only 39 percent of whites.

In terms of annual income, 60 percent of families who made under $50,000 voted Democratic compared to 45 percent who made over $50,000.

In 2009, St. Paul Mayor Chris Coleman won with 68 percent of the vote. Mayor Rybak took 74 percent.

“Any quality Republican is not likely to run for office in an urban area. They’re more likely to run for office in a suburban area, an exurban or a rural area,” Pearson said.